What do climate projections say about future droughts in Alabama and the Apalachicola-Chattahoochee-Flint River Basin?

View/Open

Date

Author

Type of Degree

Department

Metadata

Abstract

Droughts, often considered the costliest natural disaster, are triggered by severe shortage of water, mainly in the form of precipitation. The Southeast US has been affected by frequent severe droughts in recent years and this calls for a more pragmatic approach to better manage its consequences. The primary objective of this study was to analyze how droughts in Alabama and ACF River Basin will change in future as a result of projected climate change. Commonly used drought indices were computed to quantify the change in droughts.
Historical and future droughts were quantified by the means of Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) and the change in frequency, severity and spatial extent of future droughts were studied using Severity-Area-Frequency (SAF) curves. Precipitation and temperature
data, regionally downscaled for the Southeast US for high emission scenario (A2), from three General Circulation Models, Hadley Centre Coupled Model Version 3 (HadCM3), Geophysical Fluid Dynamics Laboratory (GFDL) Model and Community Climate System Model (CCSM), from the Third Coupled Model Inter-comparison Project (CMIP3) archive were used for this study. Data from 1969 to 1999 were used for historical simulation and that from 2039 to 2069 were used for future projections.
The study showed that droughts similar to ones in the past would be observed frequently in future as well. In Alabama, SPI from GFDL and HadCM3 models indicated increasing frequency of droughts with more severity and increased spatial extent in the future. SPI from CCSM model indicated decreased severity of droughts in the future spread over similar area as in the past. This model indicated decreased occurrences of severe and extreme droughts but increased occurrences of moderate droughts. Similar conclusions were drawn about droughts in the ACF River Basin as well from the respective models and indices.
SPI was also correlated with groundwater levels in the Lower ACF River Basin to determine if it could be used to monitor groundwater conditions in the region. The index, when calculated at timescales between 9 and 12 months, showed strong correlation with groundwater levels in many groundwater wells in the region. The results suggested that it can be used as a tool to monitor groundwater conditions and hydrologic droughts in the Lower ACF River Basin.
The results of this research can be used by policymakers to plan ahead of time for better preparation of drought years. If droughts can be projected well ahead of time, their consequences can be tackled more appropriately. The results will also help us understand expected changes in droughts in the Southeast US and would help us prepare better to mitigate the economic, social and environmental effects of droughts.